Flow regulator



Feb. 23, 1943. l E, T, vJOHNSON 2,312,251`

I F-Low REGULATOR Filed Feb. 1o, 1940 a sheets-.sheet 1 A m v ventorEmil U23/25725072.

Kwam/Laag l D Bg* E herently highl iillneil il., Bloflinsom West @romigelil. il., esslsvior to il. it@lierreu meornoreteoi, Wet-st (license, aeornoretien oil New l'leteey l5 Claire-ita i rlevices tor regulate i nllulde, enel more pare A.iroveii construction regulating device Thisinventif ing,y or oootrolli ticulerly to e. s. o pilot-type seltene Theinvention is especial, icerneci with the provision in suoli regulatingriz, vses of improve ments which will render loe i vices highly sen=1sitive in operation and. :tree from rislr or damage to its parts tvl nsnl'riectell to a Wide renee of oneretlng ooi Les.

Regulating devices ot the type controlled oy pilot valves comprise arrlairl valve which is operl1 eterl ioy a pressure differential acrossan actu ating means suolo as o piston or diaphragm, ln. a typicalinstance, the pressure on one side of the valve-actuating means is thatat the inlet side of the main valve while the pressure on the other sideof the actueting inea-ris is reduced in accordance with the condition ofthe medium which is regulated by the main valve. Such conu trollecireduction in pressure is commonly ohm tained from e liypsss around themain valve having e restricted opening to the inlet side oi? the inemvalve anal having a pilot valve conf trolling the release o pressure*from the by-pass to the outlet side ci the main valve.

Velveeetueting means of the piston type are in many cases unsatisfactorybecause of leakage and weer., and tendency towards sticking; lilleEwise, those oi" the diaphragm type ere in many cases unsatisfactory,particularly because fallaa ohra-gms have little extensibility end arein y stiff. In fact, when diaphragme are used they are frequently madelarge in di= emeter in order that they will Yoe capable of suf iloientiexure to provide the necessary valve stroke and he flexible enough topermit a fairly sensitive regulating action; this has, howeverv resultedin bulky constructions which are Wholly out of proportion to the size ofthe main valve, L

In cases where a highly sensitive regulating action hes been desireel. asensitive valve-acto.u ating means has been employed which is either irlthe form oi a diaphragm mafie of a highly compliant material suelo as erubber composition. or in the form of a metal ioellovvs mede for example of phosphor bronze. Of these tvvo types of valveectuetinrf; ineensthe metal `ioellovvs is preferable because it is e compactfcrni ofdevice having both high flexibility enel high eiitensibiln ity: also e,metal bellows is considerably more durable than the rubberwcornposltiondiaphragm unless the latter is made relatively heavy, in which case theflexibility and extensibility of the diaphragm will however loe nolonger comparable sation il@o ieee, Seriell Non, llliiii to those oi e'bellows Highly sensitive forms valveuactneting means have, however, seengreatly restricted in use, is nov/v expleioerl,

in messy valve enoiicetions the initial joeesm sure is hielo, being oiz'the order o more pounds )per square moli. Wirren in socle eine tionsthere is employes; usuel. loym pilot valve erraneement los eontrollinLasure clierential eoross the valvemoet'lt ineens as eforementir 'there itimes high pressure eiitererltlele ac ating means. Since el highlyactuating ineens, anch es a bellows or a rubbeicomposition cliaohreenii,elo-es not sufficient strength to vvithsteinrl high 'pre sureferentials, these actuating roeonslieve been s where the init pressureis lotv enti Thus in iotv regulators, e range of epnlicotlons enti l'iwil. L not gone hand in hand, but lieve rather been tained at theexpense of one to the otliee lt is an object of my invention to provideo flow regulator which is loot/lt highly sensitive e, tl applicable to aWide range of operating eonliitions without risk of damage to its perte.

t is another object to provide a pilot-'Evite self-operated regulatingdevice which is "ootlf, highly sensitive and depencleiole in oyeretionuAnother object is to provisie e. sensitive leting device which. issafely ogvereole in lines vvhere the pressure may very through vvltlelimits end attain high values.

Another object is to provide a small enel construction of self-operateclregulating lieviee having e, high regulating cepeoity.,

lt is a further object to provide means by which the pressueerllilerential the vaiveactuatlng means moy loe llroitetl topredetermined velue.

lt will he understootl that tia invention as above noteert typeselifoperoted reeulotirig ti. such for example .as to devices forresillai temperature, pressure, or supply e, limiti; efurthermore, thatin viert7 of these feutres pressure et the inlet oi the pilot valve maywidely and attain high values. l

It is another object of my investiert to provide in pilot valveimprovements; ley which the valves ere rendered substentialiy comoletelyhelanceei with respect to the pressures at their inlets lt is also amobject el invention to provisie highly accurate pilot valves sensitivesuitstsrlm tially only to the condition of the medium contrailed.

' ncther object is to provide pilot valves of im-s 'gvroved constructionand of improved sensitive ness and dependability of operation.

Various features of my invention reside in novel constructions andarrangements by which the abovementioned objects are attained.

Other and allied objects and features of my invention will more fullyappear in the following description and the appended claims.

in the description of my invention reference is had to the accompanyingdrawings, of which:

Figure 1 is a view principally in section of a pilot-type self-operatedpressure regulating device in which my invention is incorporated; and

Figure 2 is a view principally in section of a thermostaticallycontrolled pilot valve constructed in accordance with my invention; thispilot valve is particularly adapted for use with the main valveconstruction of Figure 1, with which construction it forms a pilot-typeselfoperated temperature controlling regulator.

The invention is illustrated in Figure 1 in connection with a pressurereducing regulator. This regulator comprises a main valve construction Chaving a main valve i disposed within a housina 2 provided with inletand outlet ports 3 and il. IThe main valve i is of a well-known balancedtype (i. e., a type which is balanced with respect to the pressure atboth its inlet and outlet) and is adapted to reduce the initial orsupply pressure of the uid at its inlet to a desired terminal ordelivery pressure at its outlet; the Valve is self-operated or actuatedby the pressure of the huid at its inlet and is controlled by a pilotvalve il, this pilot valve being operated and controlled by the pressureat the outlet of the main valve as is hereinafter explained. It will beunderstood that while 'I n ow illustrate my invention in connection witha particular type of pressure reducing regulator, no unnecessarylimitation of my invention to this type of regulator is intended.

The selfoperating or actuating means for the main valve i comprises anexpansible and con tractible means preferably in the form of a bellowst. This bellows is disposed within a compartrnent formed by a circularbase l, having a downwardly extending boss il which is threaded into thehousing i, and by a casing 9, in the form of an inverted cup, which issecured uidtight bv bolts i to a iiange i of the base T. A lower fianget of the bellows E5 is clamped against a raised portion or boss l of thebase i but `not necessarily in a way to effect a uidtight connectionbetween the bellows and the i; this clamping is effected by way of anannular ring `ii which ls fitted between 'the casing and the base withinan annular recess El' in the casing and overthe boss 'i" and ilange tioi the bellows (the ring being suitably split to permit it to be placedover the flange 5') and which is clamped tightly against the base by thebolting oi the casing to the flange 'i'. Extending upwardly from thebase 'l' within and throughout the greater part of the length oi thebellows t is a hollow boss i2 and passing upwardly through this bossaxially of the circular 'base 'i is a stem i3 of the main valve i. Thisstem is coupled, in a manner hereinafter explained. to the upper head ofthe bellows ii and is biased downwardly, to normally hold the main valveclosed, by means of a compression spring i5 coiled about the stembetween the main valve and the top i2' of the boss i2.

In the structure just described there is formed a chamber between thebellows E and the base l and another chamber ib between the bellows andthe casing 9. The diierence in pressure between these chambers (i. e.,the pressure diierential across the bellows E) determines the amount ofexpansion or compression of the bellows and therefore the extent o1opening or closing of the main valve i. This pressure differential maybe obtained from a by-pass across the main valve and may be controlledby a pilot valve provided in the by-pass. A usual form of such by-passmay be realized by providing holes i9 in the top or" the boss i2 (toform a communication between the inlet side of the main valve and thechamber il) and other holes 20 in the head ifi of the bellows d (to forma communication between the chambers i 'i and i8) and then by couplingthe chamber i3 to the outlet side of the main valve through the pilotvalve 5 as by way of a conduit 2i which connects the chamber iii to theinlet port 5' of the pilot valve and a conduit 22 which connects theoutlet port 5" of the pilot valve to a pipe 23 leading from the outletside of the main valve, this latter connection being made, for example,by way of a Tcoupling 2li. The flow capacity of this by-pass, when thepilot valve 5' is fully open, is at least partially limited by the holes2@ between the chambers il and IS, and may typically be predominantlylimited by these holes, by making theow capacity of the holes 2@ smallin comparison to both that of the holes i9 and that of the couplingbetween the chamber iii and the outlet of the main valve. As a resultthe internal pressure of the bellows will be substantially the same asthe supply or initial pressure of the main valve; however, the eaternnal pressure of the bellows will be normally re duced because of thepressure drop across the restricted portion o the by-pass (i. e., acrossthe holes 2@ between the chambers i 'i and i 8), the amount of thisreduction depending upon the degree of opening of the pilot valve 5 andupon the delivery pressure at the outlet of the main valve.

It will be seen that in the by-pass as just described the pressure dropacross the bellows will under static conditions be substantially thesame as that across the main valve so long as 'the ow capacity of theby-pass is limited predominately by the restricted holes 2li between thechambers ill and i-L e., in the present instance so long as the openingin the pilot valve is substantially greater than that of the holes 2G between these chambers, Because of such possible pressure relationship theactuating means for the main valve has had to be made strong, forexample by the use of a stiff metal diaphragm, so as to be able towithstand the pressure difierenn tial across the main valve. When on theother hand a highly ilexible actuating means such as a bellows/has beenemployed, the regulator has been necessarily restricted in its use toapplications where the supply pressure is low in order to avoidexcessive strain of the actuating means. Thus. the bellows-tvpeactuating means has been restrlcted to a very limited field.

It is, however, a feature of my invention to pro vide simple means whichpermit highly flexible yet inherently weak forms of valve-actuatingmeanssuch for example as the bellows-type acm tuating nieansfmto usedwithout restriction with respect to the values of the supply and deulivery to and trom the valve or with respect to variations in thesepressi in Vaccordance with this feature l.' construct a compact iorm oregulator highly sensitive and which is yet wholly free :from risk ofdamage to its parts even though it is sub looted to a wide range ofoperating pressures. To effect these results l provide a relief valvebetween the chambers ll and lil (i. e., across the bellows in shunt withthe restricted portion of the ley-passi which has a capacity that islarge in relation to the capacity which the 'oy-- pass across the mainvalve would have were there unrestricted communication across thebellows ii between the chambers lll and it; this valve is normally heldclosed but ls set to open whenever the pressure differential across thebellows er seeds a predetermined value somewhat in excess of thatrequired to fully actuate the bellows t.

The relief valve abovernentioned, which appears as is preferablyprovided in the head it of the belle his valve may comprise a seat ringv be fitted in a hole M the head or the bellows aan. he heid in place bya disk-shaped not 2l which is threaded on the seat ring. The seat ringcrovided centrally thereof with a valve oort cooperating with this portis a cone-shaped closure member 25') which is mounted on areduceddiameter portion iti of the valve stem ifi, this portion i3'passing through the valve port Threaded on the upper end of the portionle' of the valve stern til and locked in place by a loclt nut @il is acircular member 3l in the'torrn oi a cup, the hub 3l o which bearsagainst the closure member 2t to hold it firmly ln place. This circularmember impinges against the too of the casing to limit the openingmovement ci the main valve. Inter nosed between the member Si and thenut 2li on the seat ring' is a compression spring @il which. presses theseat ring 25 against the closure mem ber to normally hold the reliefvalve closed, this relief valve being'however opened whenever thedifferential pressure on the head of the beli restricted when thecircular member is in Contact with vthe top of the casing 9. The holes2t, which provide the restricted communication between the chambers iland l@ as aforementioned. are preferably provided in the closure member2li as shown in Figure l.

t regulator incorporating the relief valve just described may as atypical example have the fol lowing characteristics: The size of thebellows il may be of the order of four inches in. diameter and fourinches in height. i bellows of this size maybe constructed to safelywithstand a pressure differential of 20 pounds per square inch and topermit a valve strolte of one inch. The lexibll ity of such a bellows islarge; in fact, the bellows may be expanded guiciently to completelyopen a balanced type of valve such as the main valve l. against theforce oi the valve-biasing spring iti, when the pressure dierehtialacross the beim lows is only of the order of a pound per square inch.The relief valve may be set to open when the pressure differentialacross the bellows eil" ceeds by a suitable margin that required totolli open the main valve, this diierential pressure aty which therelief valve is set to open beine', how ever, well within the maximumdiderential pres-- differential 'the dating lors .i so to prevent anyundue strain oi this bellows.

It is important that there occur large sudw den changes in pressure inthe chamber lll within the actuating bellows this is because suchpressure changes may lproduce large pressure dit1 erentials, of atransient nature, across the bei:n lows by reason of the fact that thereis neces sarily some time lag in the distribution of a pres sure changethroughout the chamber iii outside the bellows in response to a pressurechange in the bellows. Consequently, l prefer that the communicationbetween the inlet side ot the valve and the chamber il within thebellows be somewhat restricted to prevent a too rapid rise .in pressurein the bellows; this restriction may for example be provided by limitingthe size ci the holes l@ to about twice that of the holes be tween thechambers il and illA It will be seen that while the relief valveprotects the actuating bellows ii from damage it will in no way impairthe normal operation of they regulator so long as the operation of thetoilet valve d is independent of the pressure at its in* let-which is acharacteristic of the pilot valve as ls hereinafter explained; this lsbecause limiting of the pressure diierentlal across the actuatingbellows to some value which is cess o that required to onen themainvalve will not affect the valve movement, for the valve is thenalready fully operi, but will only prevent the actuating bellows frombeing subjected to un necessarily high differential forces.

The ability of a pressurewreducing regulator to maintain a deliverypressure within narrow li its is, among other things as heretoforenoted, dependent upon the accuracy and the sensitivity of the pilotvalve. The dfegic s et accuracy oi? i pilot valve may be represented bya factor e pressing the ratio oi' the influence on the valve o thepressure at its outlet (i. e., the delivery sure from the main valve tothe iniiuenceon the valve oi spurious effects such for example that ofthe pressure at its inlet; and the d of sensltivityof the pilot valvemay be rei je sented by a factor expressing the ratio of change of valveopening per unit change in the pressure at the outlet of the valve. Theproduct of these factors may then represent a rieure oi merit for thepilot valve. In the instant invention, the

.pilot valve is so constructed as to have ceptionally large figure ofmerit. First the factor representing the degree of accuracy of the pilotvalve, as above defined, is made particularly large by a constructionwhich renders the opera-- tion of the pilot valve wholly independent cithe pressure of the fluid at its inlet; and the factor representing thedegree of sensitivity of the pilot valve is made unusually large byconstruction which permits the valve port to made large l this portbeing permitted to be made large without a sacrifice in the accuracy ofthe regulator by reason of the construction which renders the operationoi the pilot valve inthen pendent of the pressure ot the huid at itsinlet). The construction of this nilot valve is now de-l scribed.

The pilot valve Ei comprises a housing hav lng the inlet and outletports il' and 5 abovernentloned, between which located a partition iid.This partition has an opening into which is threaded a valve seat havingvalve t?. The valve port tl is adapted to be closed oy a valve throttle323 which is slidably mounted on. ide post titl; this post passesaxially through err, .lll and is extended through a boss housing lit, towhich the post is rigidly held by a nut 39 threaded on the outer endportion of the post.

ler that the operation of the pilot Valve .vii independent of thepressure at its inlet it is balanced with respect to that pressure. Themeans by which this balancing is effected com-` prises an invertedcup-shaped casing lll which is threaded onto the valve throttle 38 as at422.. This casing is closed at its top by a plug 43 which is held inplace by a cylindrical nut M. Within the casing between the plug i3 anda base lib formed on the post 39 is a bellows 5. This bellows is sealedfluid-tight, as by soldering, to the base it and plug 43 and is filledwith gas by way of a vent ll'i running up through the post 38, whichvent may be closed after the lling of the bellows by a plus.r fit. Inthis construction the effective diameter of the bellows 45 is made equalto the eective diameter of the valve throttle, which diameter is that ofthe lower flat face Sil ci the throttle. This face 38 of the throttle isperforated by holes tg so that the chamber formed between the casing 6iand the bellows dii will 'be in communication with the inlet side ci thepilot valve. As a result, the forces exerted by the pressure atjtheinlet of the pilot valve against the top and bottom of the valve'throttle within the diameter of its face S8' will be equal andoppositely directed; likewise, the forces ei:-

within the casing il by the inlet pressure against the top oi the casingand the area. at the betteln oi the casing beyond the valve face will beequal and oppositely directed. rlhus the eect or the pressures exertedfrom the inlet side of the pilot valve upon the throttle 38 and casingdi is reduced to a nullity; this reduction holds substantiallycompletely regardless of the position ci the throttle in its path,thereby rendering 'the pilot valve balanced at all times with respect tothe pressure of the fluid at its inlet.

it will be seen that the huid at the outlet ol the pilot valve is infree communication with the exterior of the casing it and throttle 32except ior the face tti' of the throttle. Since the assem- 'bly thethrottle til, casing di and bellows l5 is balanced with respect to thepressure exerted on the face tii, as just explained, this assemblybecomes unbalanced with respect to the outlet pressure oi' the pilotvalve to the extent of the force exerted by the outlet pressure on thehead or ton of the casing (i. e., at a place directly opposite the face33' of the throttle) over an area equal to that of the face til'. rIheforce on the casing as created by this unbalance is effective close thethrottle fili'. y

pressure' in the bellows t5 acts to bias the th cle into openposition-which position is donned by the Contact of the throttle withthe Since the bellows i5 is typically small ill be able to withstandhigh pressure differaccordingly' the biasing of the throttle Sli fsafely set at any predetermined value .t o wide range by controlling thequantity s ejected into the bellows. The biasing is y rendered readilyadjustable either by cing,T or counteracting the biasing eiect bellowsas by a suitable spring. In the instance, the bellows lill is iiiledwith a oi? gas sufficient to hold the throttle maximum delivery pressurewhich.

Eli)

" jnlator may be called upon to maintain, 753i and counteracting thebiasing eiiect of the bei lows d5 is a repression spring lli which isadu `instable so i fillet tr-alive operate (i. e., to close) atpreassigned de feria pressures below the maximum value just reen tioned.

The compression springr is positioned ve the bellows between a cap lltthreaded into the cylindrical nut lll and an adjustable cap E53, and isdisposed within a casing l which is coupled huid-tight to the housing33, the casini; 5ft having a iiange resting on an open enel 33' of thehousing and being held in place by an annular coupling threaded onto thehousing. Between the casing and the housing 33 there is provided apartition fait which has a central opening lib through Awhich sliclablypasses the cylindrical nut itil; this partition serves. as e guide forthe throttle assembly (i. e., the assem bly including the throttle 35i,the casing di, nut 12A and can 52). Into the top or the casing there isprovided a boss 5l through which is threaded a screw bil, the lower endoi which fits into a recess 53 in the cap This screw pro- 'vldes meansfor moving or adjusting the cap to control the degree of compression oi'the spring 5l and therefore the net biasing of the throttle dit.Threaded over the 'boss el is a cover il@ which, serves to close the topci the casing il@ huid tight.

Because the pilot valve i5 is so arranged as to be substantially whollybalanced with respect to the pressure of the fluid at its inlet theaccuracy of the pilot valve will not be impaired when the diameter ofthe valve' port tsl is made large. In unbalanced pilot valves such, forexample, as those employing a diaphragm as the actuating means for thevalve throttle, a fairly high degres of accuracy has been attained onlyby causing the ratio between the eilective area oi. the phragm and thatof thevalve port to be large. Indeed in many typical instances thisratio been so large that when the diaphragm is made as large as severalinches in diameter the valve port is yet held in diameter to `within asmall fraction of an inch. However, in the present instance in view cithe balanced character ci the valve the diameter or the valve port maytypical lybe an inch or incre in diameter, thereby en abliner thesensitivity factor for the valve to be made particularly large.

Irl Figure 2 there is shown a pilot valve tti, controlled by athermostat lil, which may he connected in the by-pass across the mainvalve o Figure l, in place oi the pressure controlled pilot valve 5, soas to effect a pilot-type self-operated regulator for temperaturecontrolling purposes. Such a regulator may for example be employed tocontrol the temperature of liquid contained in a tank T (partiallyshown), which liquid may be heated by steam controlled by the main valvei and brought into thermal relation with the liquid in the tenir in anydesired manner. The thermo stat tl may be mounted on the tank T so thatit will be maintained at the temperature ci liquid in the tenir andthereby control the pilot valve in accordance with temperature of thisliquid. in such a temperature controlling regulator the main valveconstruction may be identical to the construction C heretofore describedin connection with the-pressure reducing regulator; accordingly theremay be again obtained the advantages in sensitiv and safety of operationheretofore noted t connection 'with t main valve construction asiaticiThe pilot valve to, like the pilot valve t, is con strected so as tohave a large usure of merit both in respect of accuracy and sensitivity.In

this case the factor expressing the accuracy ofpesatura of thethermostat di; and the factor expressing the sensitivity is made largeby employ- "ins a volatilizing principle hereinafter explained.

' The pilot valve d@ comprises a housing o2 which may be oi the samegeneral form as that of pressure at the outlet oruieellot telve te sathe throttle 65 is completely nulliiied, thereby leave ing the pilotvalve' balanced with respect to that pressure. The lbellows il may notonly maire possible the balancing of the pilot valvewith respect to itsoutlet pressure but may alsdan inl the case of the pilot valve8,'constitute a means for biasing the throttle 65 into open position-ewhich position may be defined by the contact of the throttle with thebase 13. This'biasins may be set to any predetermined value by villlinathe bellows with gas by way oi a vent te' extend ing axially through theguide post ab, which the housing Sil or the pilot valve t; this housinghas the inlet and outlet ports 60 and B0" between which there isprovided a partition `63 having an crimine et.

so that Aits inlet and outlet ports will be reversed The housing b2 is,however, oriented from those of the pilot valve 5. (This is done,v

as hereinafter more fully explained, in order that the duid at the inletside or the valve will be in direct contact with the operating parts ofthe` valve instead oi the huid at the outlet ofthe valve as is the casewith the pilot valve b.) Threaded into the opening de' is acyllndrically shaped valve seat te having a valve port te' adapted to beclosed by a cone-shaped throttle' de which is loosely slidably mountedon a guide `post at; this post passes axially through the valve port biland is extended through a boss t1 in the housing bt-to which the post isrigidly held by a nut @t threaded on the outer end portion of the post.

nl order that the operation of the pilot valve will be independent ofthe press'ures of the uid at its inlet and outlet the valve isconstructed so that it is balanced with respect to those pressures. Themeans by which the balancing of the valve with respect to its outletpressure is accom plished comprises a cylinder de which is threaded atits bottom into circular recess S5 in the throttle bil and which isclosed at its top by a. cap lil threaded onto the cylinder. Within thiscylinder there is provided a bellows 'il having a. head l2 at its topand secured at its bottom to a base it formed on the top of the guidepost 8B, the

bellows li being sealed airtight, as by soldering,

to the head 'l2 and base 13. The head 12 has an upwardly extending boss'it about which there is fitted an annular disk 15; this disk isswivellingly connected to the head by a washer 1B ntting about a shortcentral post 11 on the boss and held in place by a peening of this post.Within vent may be closed bya plus 66" alter the lling of the bellows. l

The means for balancing the with respect toits inlet pressure comprisesa bellows 19 (which serves also as o. motor bellows as is hereinafterexplained). This bellows is oi' the same eiective diameter as that ofthe bellows 1i and is soldered at its bottom to a iiange d@ provided ona boss el of the cap 'ld and'at its top to a flange 82 of a plug 83. The"plus et extends axially through a cap 8e which is thread ed as at 86into the housing 62. The cap de has an interior recess im' into which isydisposed the ilange 82 of the plug 83, the flange being rmly heldagainst the top of the recessed by a nut iid threaded onto the outer endportion of the plus.

The nut 86 is provided at its bottom portion with an annular recess BBso that the nut may t an annular disk 81 to hold this disk in place atthe top of the cap 84. In the construction here der scribed theconnections between the cap te and housing 62 and between the cap 84 andplus' et which the inlet pressure acts to urge the throttle the cap lothere is provided en annular shoulder it which, when the cap is threadedonto the cylinder, bears against the rim of the disk 15 to hold lttightly against the upper end of the cylinder. Itis seen that allexterior parts of the assembly just described-which exterior parts in#clude the throttle b5, cylinder 69 and cap 10-are swivellingly connectedto the head 12 0f the bellows l i. This is done in orderv that duringthe assembling of the parts the bellows will be re lieved of possibletorsional strain.

In the structure just described the throttle 65 is tted loosely on theguide post 63, as aforementioned, in order that the Huid at the outletof the pilot valve may be in direct communication with the chamberformed between the cylinder et and bellows 1i; also the effectivediameter oi the bellows 1i is made equal to that of the valve port dll.In so doing there is realized from a functional standpoint the sameconditions as are hereinbeore explained in connection with the pilotvalve t, in view of whichthe eect of the open are; exactly equal to thesurfaces against which the inlet pressure acts to urge the throttleclosed, thereby leaving the pilot valve balen with respectto its inletpressure.

f' The upper portion oi the throttle assembly is positively'guidedduring the opening and closing of the throttle by a simple meanscomprising a boss 83' extending downwardly from the'plux 83 within thebellows 19 and terminating into an abutment or knob 83", and atelescoping tubu lar portion 8l' extending upwardly from the boss 8|within the bellows 19 and slidably fitting the knob 83". In order thatthis guiding means may also serve to prevent the bellows it frombeingstrained by excessive stretchingas may be caused by the handling ofthe parts during the assembling of the pilot valve-the tubular portion8|' is peened inwardly at its top, as at B8, to form a stop withthe'knob Se. This peening is done very simply by providing e, V-shapedrecess 89 in the plug 83 at the juneture between the boss B3 and theilange di, and

by pressing the tubular portion 3i up into the 'pilot' valve ed opening,and then providing an opening 92 in the tubular portion 8|' so that thechamber within the tubular portion 8|' and the chamber between thistubular portion and the bellows 19 will be in free communication withone another. The thermostatic bulb 6| and capillary tube 90 are lledwith liquid. As the temperature in the bulb risesk and falls this liquidexpands and contracts accordingly to cause liquid to be injected intothe bellows 19 during a temperature rise and to be removed during atemperature drop. In cases where a highly sensitive pilot valve isdesired the thermostat 6| and capillary tube 90 are completely filledwith a volatile liquid adapted to volatilize at .the operatingtemperature of the motor bellows. When the motor bellows is directlythermally exposed to the fluid from the inlet side of the pilot valve,in the manner as heretofore explained, its temperature will besubstantially the same'as that of the fluid controlled by the mainvalve; thus when a liquid is chosen for the motor system of the pilotvalve that has a volatilizing temperature substantially below that ofthe fluid controlled by the main valve, the liquid introducedinto themotor bellows 'l0 by the thermostat 6| will be volatilized immediatelyfollowing itsentry into the motor bellows. Since such volatilization` isaccompanied by a large expansion in volume it will cause the action ofthe pilot valve to be highly sensitive to the temperature oi thethermostat. If, however, a highly sensitive pilot valve is not requiredthe motor system for the pilot valve may be actuated by mere liquidexpansion. In this case the liquid chosen for the thermostat is onewhich will not volatilize at the operating temperatures of the pilotvalve; when such a liquid is used not only the thermostat 6| andcapillary tube 90 are completely filled with the liquid but also themotor bellows 19.

It is preferred that the volatilization principle be employed in themotor means of the pilot valve 00 since in the particular pilot valve asabove described the use of this principle produces not only a highsensitivity but also an unsualiy high degree of accuracy. Since thethrottle 65 is biased open by a closed gas chamber (that is, the bellows1|) this biasing will vary with temperature in accordance with the lawsof a perfect gas. When the volatilization principle is employed in themotor means of the pilot valve the liquid in the bellows 19 will becompletely vaporized immediately following its entry into the bellows.The pressure created in the motor bellows by this volatilization isprevented from backing up-into the thermostat by reason of thethermostatic bulb 6| and capillary tube 90 being lled with liquid. Thusthe motor bellows 10 constitutes in effect a closed gas chamber whichalso behaves according to the laws of a perfect gas. Since thetemperature of the bellows 1| will be maintained substantially at thesame value as that of the bellows 19- which temperature is that of thefluid entering the pilot valvethe pressure variations in the bellows 1|and 19, as caused by variations in the operating temperature of thepilot valve, will be equal and oppositely directed, thereby renderingthe operation of the pilot valve independent of its own temperaturesolong as its temperature is high enough to maintain completevolatilization of the liquid introduced into the motor bellows 19. Whenlthe volatilization principle is not used 4the motor bellows 19 will befilled at all times with'4 liquid as heretofore 75 noted. This liquidwill have a different thermal coeflicient of expansion than that of thegaslled bellows 1l, and therefore the pilot valve will be somewhatsensitive to its own temperature.

When the volatilization principle is employed it is important that therebe provided a cooling chamber at the juncture of the capillary tube withthe motor bellows i9 in order 4that the region of transition from gas toliquid in the motor system will be rather sharply defined. Such acooling chamber may comprise a perforated cylinder 94, which may forexample be made of monei metal. This cylinder is clamped between a coverplate and the cap 80 (which cap is recessed as at 96 to receive thecylinder) by means of screws 91 which pass through the cover plate andthread into the annular disk 0l.

` be protected from excessive strain, the securing of the armor to thehousing being effected by the provision of a pair of lugs 99 turned downfrom the-cover plate, between which the armor is soldered or clamped asby screws |00 threaded through the lugs.

The thermostat 0| is provided with the tubular bulb 6|' having anormally closed inlet opening |0| at'its lower end. The upper endportion of the bulb 6|'.is fitted into a sleeve |02 and the sleeve is inturn tted into a counterbore |03 of cylindrical member |04, the jointsbetween the bulb and the sleeve, and between the sleeve and the member|0 being each rendered fluid-tight as by soldering. The intermediateportion of the cylindrical member |04 is tapered to form a seat |05 fora rotatable union coupling |06 which is held on the seat lll@ by a nut|01 threaded on the member it, and the coupling |06 is externallythreaded for attachment to a support as for example to the tank Taforementioned.

In order that the capacity of the bulb 6 l may be varied it is closed atyits top by an axially movable plunger |08, the plunger being sealed tothe bulb by means of a bellows |09 soldered at one end to a ange 0 onthe plunger and at the other end to a flange at the top of the bulb 6|.axial opening ||2 through which passes the capillary tube 90, the topportion of this opening being counterbored and lled with solder toprovide an air-tight seal between the tube and the plunger., Threadedonto a neck portion |00' of the plunger is a cylindrically-shaped capH3. This cap is provided with an outwardly anged portion ||3' at itslower end into which is threaded a set screw i I4 which bearsagainst theneck portion |08' of the plunger to hold the cap in place on theplunger. Also extending through the iianged portion H3 is a pin H5 theouter end portion of which slidably engages a longitudinally extendinggroove ||6 in the inner wall of the cylindrical member |04. Theengagement of the pin H5 with the groove IIB permits movement of theplunger longitudinally of the cylindrical member |04 but preventsrelative turning between the plunger and member |04, thereby protectingthe bellows |00 from torsional strain. The upper portion of the cap H3is provided with an axial opening H1 through which passes the capillarytube 90. This opening is The plunger |08 is provided with an 'ordinatelyhigh values.

2,312,251 I- counterbored, as at l, and iitted with the flexible casingSii', which casing is'secured to the cap as by soldering. Threaded ontothe top of the cylindrical member it is a nut H9 which slidably ts theupper end portion of the cap iid. Between this nut and the flange H3 onthe cap is a compression spring l which urges the plunger inwardly ofthe thermostatic bulb di', the inward movement of the' plunger beinghowever restricted by the contact between the nut i2 and a nut l2ithreaded on the top of the cap H3. By an adjustment of the nut 'I i9 onthe cylindrical member IM the plunger may be moved relative tothethermostatic bulb `6l' to vary the capacity of the thermostat. l

In the operation of the temperature controlling regulator hereinabovedescribed the therinostat 6i may at times be subjected to unusually hightemperatures, causing the pressure in the motor system of the pilotvalve to reach in- This may cause a rupture of the motor bellows 19, orof the bellows it@ in the thermostat, or even of the capillary tube 9U.To prevent suchdamage to the motor system of the pilot valve I haveprovided a pressure relieving means jin'the form Voi'the spring IED;This spring is set so' that when the pressure in the motor systemreaches an upper limit the spring will begin to yield to thereby preventthe pressure in the motor system from rising substantially above suchlimit. r

Although I have herein shown and described my invention in terms ofcertain speciilc embodiments, it will be understood that theseembodiments are subject to many changes and modifications withoutdeparture from the scope of my invention, which I understake to expressaccording to the following claims.

I claim:

l. In a fluid-controlling device having a structure comprising a mainvalve movable between open and closed positions, an extensible and con-'tractible means connected to said main valve and a controlled by-passaround said main valve including a pilot valve and having a restrictedportion adapted to cause a localized pressure drop in the 'by-pass,ysaid pressure drop being applied across said extensible andcontractible' means and actuating the latter to move the main valvebetween Iits said positions: the combination of a relief valve, disposedin shunt across the restricted portion of said by-pass, for limiting thepressure diierential across said extensible and contractible means; andbiasing means, carried with said main valve and without inuence on thesame, for holding said relief valve closed until the pressuredifferential across said extensible means reaches a value in excess, bya predetermined amount, of that required to cause said main valve to bemoved through its range of movement.

2. In a structure having a main valve for controlling the ilow of aheating iiuid, a chamber, and extensible and contractible meansconnected to said main valve and forming a movable partition betweensaid chamber and the inlet side of the main valve: the combination of aby-pass around the main valve including said chamber, said lay-passhaving a restricted portion between the inlet side of the valve and saidchamber normally causing a pressure drop across said extensible andcontractible means; a normally closed relief valve between said chamberand the inlet side of said main valve for limiting the pressure dropacross saidextensible and conv operation of the pilot valve independentof the tractible means, said relief valve beingopened in response to apressure `differential thereacross in excess of a predetermined amountand causing the minimum pressure in said chamber to be not below thepressure at the inlet side o! the main valve by more than to the extentoi' said predetermined amount; and a thermostatically controlled pilotvalve in said by-pass -for controlling the flow of'fluid `from saidchamber to the outlet side of said main valve, said pilot valvecomprising means causing the'valve to be balanced with respect to thepressure at its inlet side whereby to render the operation of the pilotvalve independent 4voi variations of the pressure within said chamber.

3. vInv a structure for'reducing pressure comprising a' main4 valve, aby-pass around said valve having a restricted opening to the inlet sideof the valve, achamber communicating with said by-pass, and anextensible and contractible member associated with said valve andforming a partition betweensaid chamber and the inlet sideof the valve:the combination of a normally closed relief valve between said chamberand ysaid inlet side of the main valve, openable in response to apressure differential across said extensible and contractible member inexcess of a predetermined amount and causing the minimum pressure insaid chamber to be not below the pressure at said inlet side of the mainvalve by more than to the extent of said predetermined amount; and anormally open pilot valve in said by-pass between said chamber and theoutlet side of said main valve closeable in response to the pressure atits outlet, said pilot valve comprising means rendering the valvebalanced with respect to the pressure at its inlet whereby toV renderthe pressure in said chamber- 4. In a structure having a main valve forcontrolling the flow of a heating fluid, a chamber, and extensible andcontractible means connected to said\main valve and forming a movablepartition between said chamber and the inlet side of the main valve: thecombination of a by-pass around the main valve including said chamber,said by-pass having a restricted portion between the inlet side of thevalve and said chamber nor mally causing a pressure drop across saidextensible and contractible means; a pilot valve in said by-pass betweensaid chamber and the outlet side of said main valve, adapted to respondto the condition of a medium to be regulated and to thereby control therelease of pressure from said chamber in accordance with the conditionof said medium; and means within said pilot valve for balancing thelatter with respect to the pressure .at its inlet whereby to render thecontrolling action of the pilot valve independent of the pressure insaid chamber, comprising a movable vessel disposed in the outlet side ofthe pilot valve and provided with an apertured base forming a throttlefor the pilot valve,

- and a bellows within said vessel having end walls chamber `and theinlet around l, :garanti V- sidof the the combination of a controlledby-pass said main valve adapted to provide a dii.-4 l

torrential pressure across said extensible and conf-z tr lneiurine saidchamber-'and having arestricted Tele means to actuate the same, saidlav-'pass restricted portion being adapted to cause the:

pressure in said chamber to'. be normally substan-y melig; lower thanthe pressure at the inlet of the 1f .1'

n valve, the pressure in said chamber how# eveu attaining the value ofthe pressure at the. inlet oi the main valve when said pilot valve isV.iuily closed; and means included within said pilot valve ier balancingthe pilot valve with respect pressure yat its inlet whereby to renderthe operation of the pilot valve substantially wholly ,Y

independent of the pressure in said chamber.

o. in a duid regulator including a main valve extensible andcontractible means connested with said valve: the combination of means viol' utilizing the supply pressure of the i'iuid to regulator foractuating said extensible and contractible means to operate said mainvalve,

including a by-pass leading from the inlet of` the regulator and havinga restriction therein a pilot valve at its outlet, said by-pass beingndopted to cause the pressure drop across said restriction to be appliedacross said extensible and contractible means; a relief valve in shunt,with said lay-pass restriction to limit the pressure drop across saidextensible and contractible means; and means between the inlet of saidregand said extensible and contractlble means bovino an opening thereinforming the inlet of wpass, said opening being restricted to imure tosaid extensible and contractible l n duid-resulatlng device including acas.. :los having inlet and outlet ports and a regulating valve in thepassageway between said ports: the combination of a by-pass leading fromthe inlet side oil said valve and having a substantial pressure droptherein; a localized pressure-reducing restriction in said by-pass; amovable means coupled to said regulating valve and actuated by' thepressure diiIerential across said restriction; a pilot valve disposed insaid by-pass im serial arrangement with said restriction and controlledin response to variations in the condition of a predetermined medium,said pilot vulve operating to proportion between it and said restrictionthe total pressure drop thereacross to control the pressurediii'erential across movable wall means; and means included in saidpilot valve rendering the same insensito variations in pressure at itsinlet `whereby to said control valve to be controlled independentiy ofthe absolute pressure of the fluid having inlet and outlet ports and aregulatalve in the passageway between said ports: combination of aby-pass leading from the t side of said valve and having a substantialde the transfer of sudden changes of supplycontrolled in response tovariations in the con ditionoi' a predetermined medium, said pilot valveoperating to proportion between it and said restriction the 'total'pressure drop thereacross whereby tol control the pressure dierentiolacross said movable wall means; a safety leliei7 valve across saidrestriction actuatable inl re spense to a pressure diierential acrossthe same in excess oi va predetermined value for limitins the'-.maximumpressure dierential across said movable wall means; and means includedin said.,

pilot .valve for rendering the operation'of the same independent oi theabsolute pressure at its inlet whereby actuations of? said relier valveare rendered substantially without-influence on the' operation of saidregulating valve.

9. In a nuidwontrolling device having inten communicating inlet andoutlet ports, a main valve disposed in the passageway between said portsand extensible and contractible means connected to said valve andactuated by the pressure of the fluid at said inlet port to operate thevalve: the combination of a chamber partitioned from said inlet port bysaid extensible and contractible means and having a restricted inletpassageway to said inlet port; a pilot valve for control ling the escapeof fluid from saidchamber; a

relief valve between said chamber and said inlet port for limiting thepressure differential across said extensible and contractible means; andsep arate independently acting biasing means for said main valve andrelief valve respectively.

10. In a fluid-controlling device having intercommunicating inlet andoutlet ports, a main valve disposed in the passageway between said portsand extensible and contractible means actuated by the pressure of thefluid at said inlet port to operate the valve: the combination of schamber partitioned from said inlet port by said extensible andcontractible means and having restricted inlet passageway to said inletport; a pilot valve for controlling the escape oi fluid irom saidchamber; a relief valve between said chimi-E1 ber and said inlet portfor limiting the pressure diilerential across said extensible andcontractible means; and resilient means biasing said relief valve closedand operatively coupling said extensible and oontractible means withsaid main valve. y

l1. In a fluid-controlling device including a casing having inlet andoutlet ports, a main valve in the passageway between said ports and anextensible and contractible member for operating said valve: thecombination of means for applying a differential pressure across saidextensible and contractible member to actuate the same-g a relief valveoperatively connected across said extensible and contractible member tolimit said diil'erentiai pressure; resilient means operativelyconnecting said extensible and contractible member with said main valveand biasing said relie? valve closed; and resilient means interposed between said casing and said main valve and oper@ ating on the latter inopposition to the actuations of said extensible and contractible member.

12. In a fluid-controlling device including a casing having inlet andoutlet ports. a main valve in the passageway between said ports and anexe tensible and contractible member for operating said valve: thecombination ci' means for apply= ing a dlierential pressure across saidextensible and contractible member to actuate the same; a valve seat onsaid main valve; a valve member secured to said extensible andcontractible member, said valve membera cooperating with said interposedbetween said main valve and said valve member for coupling said. memberto seid main valve and for normally holding said relief valve closed.

13. In a fluid-controlling device including a casing having inlet andoutlet ports, a main valve in. 'the passageway between said ports and enextensible arid contractlble member for operating said valve: thecombination of means for applying a dierential pressure across said ex-*sensible and contractible member to aotuate the seme; a valve stem onsaid main valve projecting through said extensible and contractiblemember; a valve seat en said stem; velve member surrounding said stemand secured to said extensible and eoritrectible member, said valvemember cooperating with said valve seat to orm a relief valve forlimiting the olierential pressure across said member; a stop member sencured to said stem arid adapted to abut against en interior wall of saidGesine to limit the travel oi said main valve; and resilient meansinterposed between said stop member and said valve member lor pressingtlie latter said valve seat to normally hold said relief valve closed.

lli. 1n a fluid regulator including a easing having a fluid passagewayand a main valve in said passageway: the combination oi' en extensibleand comsractiblev member comiected with said an annular main. valve andactuated by a dierential in bres sure applied to the opposite sidesthereof; a re lief valve for limiting the diereritial pressure` acrosssaid member; a biased spring eating. to yieldably hold seid relief valveclosed and re quired to be actuated against its own bias to mit saidrelief valve to open: a fixed wall in said casing; and means on saidmein valve constrain ing said resilient means and adapted to abutagainst said xed wall to limit the travel oi the main valve.

l5. In a uid regulator including a casing hav. ing a fluid passagewayand a main valve in said passageway: the combination of an extensibleand contractible valve-operating member actu ated by the diierentlal inpressure applied to the opposite sides thereof; a valve seat carriedwith said main valve; a valve member secured to said extensible andcontractible member and cooperatingwith said valve seat to form a reliefvalve for limiting the dierential pressure across said extensible andcontractible member; a fixed wall in said casing; a stop mem-ber securedto .said mein valve and adapted. to abut against said lixed wall tolimit the travel of said mein valve:

' and a biased spring acting at one end ori said valve member tonormally hold said reliei valve elosed and constrained at the other endby said stop member, said spring being required to be actuated againstits own bias to enable said relief valve to be opened.

